\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{circuitikz}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{circuitikz}[>=latex, scale=1.0,european]
  % \useasboundingbox(0.9,0)rectangle(5.1,5);
  \draw[densely dashed,thin](-1.5,0)--(6,0);
  \draw[semithick,densely dashed](0,0)parabola(4,-0.25);
  \draw[semithick,densely dashed](4,-0.25)--(6,-0.5);
  \draw[very thick] (0,0.5)--(4,0.5)(0,-0.5)--(4,-0.5);
  \foreach \x in {0.2,0.8,...,3.9}
  {
    \draw[thin,<-](\x,0.4)--++(0,-0.8);
  }
  \node at (2,1.0) {$\ell=\qty{6.0}{cm}$};
  \draw[ultra thick] (-0.5,0.1)arc(0:25:3)(-0.5,-0.1)arc(0:-25:3);
  \draw(-1.7,0.1)--(-1.6,0)--(-1.7,-0.1)[-o]--(-1.7,-2.0)node[left]{\scriptsize$-$};
  \draw[-o](-0.6,-0.95)--(-0.5,-1.05)--(-0.5,-2.0)node[right]{\scriptsize$+$};
  \node at (-1.1,-2.3) {\qty{2500}{V}};
  % \draw(0.5,0.5)--(0.5,0.75)--(-2.1,0.75)--(-2.1,-1.5)to[battery](0.5,-1.5)--(0.5,-0.5);

\end{circuitikz}
\end{document}